In practice, eggshell temperature (EST) often increases at the end of incubation due to heat production of the developing embryos and a poor cooling capacity or air velocity in the incubator. High (≥38.9°C) compared to normal (37.8°C) EST negatively affects survival and hatchling development (Lourens et al., 2005), and this may be related to changes in nutrient utilization or more specific changes in glucose metabolism.